208 



CALCAREOUS MANURES-APPENDIX. 



ly peculiar ; and its effects as manure were soon also observed to be 

 in some measure different from those of the other marls, which I had then 

 used, and which were all of the kind now distinguished as miocene. At 

 that time these terms had not been introduced, and for perhaps fifteen 

 years afterwards, I did not so much as hear of the terms " eocene" and 

 " miocene ;" but their difference of age, appearance, and agricultural cha- 

 racter were not therefore the less evident and obvious to my observation. 

 The manifest difference of effects as manures was then ascribed by me 

 to the general if not universal presence of a small proportion of sulphate 

 of lime, or gypsum, in the eocene marl. The belief in the general presence 

 of gypsum was very early induced by my seeing in a few places small 

 crystals overlying and in contact with the surface of the bed of marl ; and 

 also by the apparent results of such poor attempts as I subsequently made 

 to ascertain the presence of this substance, by means of chemical tests. 

 Upon such imperfect tests, and to the still more imperfect knowledge and 

 skill which I could apply to the investigation, (amounting indeed to almost 

 nothing,) very little reliance ought to have been placed. Nevertheless, I 

 thence inferred that there was universally present and diffused through the 

 body of this marl a small proportion of sulphate of lime, (say one or two 

 parts in the hundred,) and subsequent agricultural practice has supplied 

 the confirmation, which has not yet been sought for by the superior chemi- 

 cal knowledge and skill of any other and late investigator. In the earliest 

 publication of my views on calcareous manures in 1821, the gypseous 

 character of this particular body of marl was affirmed, and the peculiar 

 character of the results of the first experiments with it stated.* And in 

 the edition of 1832 of the 'Essay on Calcareous Manures,' the general 

 and full description of this marl was given precisely as it now stands 

 in pages 92 and 93 of the latest edition. My still earlier discovery of and 

 observations upon the peculiar character of the underlying bed oi gypseous or 

 '■^ green-samV earth, (which will be treated of subsequently,) led me to 

 observe the peculiarities of the eocene marl, which being less distinctly 

 marked, might otherwise have escaped my notice. 



As stated above, it was not from any knowledge of geological theories 

 of successive formations, and different ages and periods, of all which I 

 was profoundly ignorant, that my opinion of the peculiar character of this 

 marl was influenced. But judging solely from the more rotten and disinte- 

 grated state of the shells, and their entire disappearance generally, even 

 though their calcareous material remains — and from the total difference of 

 kind of the few shells remaining whole, or of which the shape is distinctly 

 marked, from any others of the many shells then known to me in any other 

 marls, I very early formed the opinion that this bed was one of the re- 

 mains or ruins of a condition of the earth much more ancient than that 

 in which the ordinary marls had been formed. I remember having stated 

 this opinion to one of the earliest of the several geologists who at different 

 times visited my dwelling place and my marl excavations. This was the 

 since notorious Mr. Featherstonhaugh, to whom I pointed out this curious 

 and to me highly interesting deposite, and requested his attention to the 

 more modern and very dilferent (miocene) marl lying immediately upon 

 and in close contact with the much more ancient formation below. This 

 remarkable feature I also showed at a later time to Professor William B. 

 Rogers, who was much struck with the fact, and attached so much impor- 



• American Farmer, vol. iii., p. 317, and also tli? same experiments numbered 1^, 19, 

 20, of the present edition of ' Essay on Calcareous Manures.' 



